Technical Field
This disclosure relates to a drive transmission device and an image forming apparatus incorporating the drive transmission device.
Related Art
Known image forming apparatuses include a drive transmission device that transmits a driving force of a drive motor that functions as a drive source to a rotary body such as a photoconductor.
For example, a known drive transmission device includes gears, a link device, a drive side coupling, and a driven side coupling. A driving force is transmitted from a drive motor to one of the gears that functions as a first drive transmitter. The link device drives and links the gear and the drive side coupling that functions as a second drive transmitter. The drive side coupling is engaged with the driven side coupling that functions as a third drive transmitter, and transmits the driving force to the driven side coupling. The link device includes a first inserting body, a second inserting body, and a rod-like linking member. The first inserting body has a spherical shape and is inserted into a hollow body provided in a rotation center of the gear. The second inserting body has a spherical shape and is inserted into a hollow body provided in a rotation center of the drive side coupling. The linking member links the first inserting body and the second inserting body. A drive side projection is formed on the first inserting body to be engaged with a drive side groove that is formed in an inner peripheral surface of the hollow body of the gear and extends in a shaft direction of the gear. Further, a driven side projection is on the second inserting body to be engaged with a driven side groove that is formed in an inner peripheral surface of the hollow body of the drive side coupling and extends in a shaft direction of the hollow body. Further, the known drive transmission device is provided with a coil spring that biases the drive side coupling toward a rotary body side.
When an outer peripheral surface of the spherical first inserting body slides with the inner peripheral surface of the hollow body of the gear and the drive side projection provided on the first inserting body is moved in the shaft direction in the drive side groove, the link device can be inclined with respect to the gear. Further, when an outer peripheral surface of the spherical second inserting body slides with the inner peripheral surface of the hollow body of the drive side coupling, and the driven side projection provided on the second inserting body is moved in the shaft direction in the driven side groove, the link device can be inclined with respect to the drive side coupling member. In a case in which there is misregistration of a rotating shaft center of the rotary body with respect to a rotating shaft center of the gear (hereinafter, the misregistration is referred to as a shaft center gap), the link device is inclined with respect to the shaft direction, so that a rotating shaft center of the drive side coupling can be adjusted to a rotating shaft center of the driven side coupling (the rotating shaft center of the rotary body), and the drive side coupling can be engaged with the driven side coupling. Further, an angular speed variation according to an inclination angle of the link device with respect to the gear, the angular speed variation having been caused between the gear and the link device, can be offset with an angular speed variation according to an inclination angle of the link device with respect to the drive side coupling, the angular speed variation being caused between the link device and the drive side coupling, and the rotary body can be rotated at a constant angular speed.
The known transmission device moves the drive side coupling to the gear side against the biasing force of the coil spring. Consequently, the drive side coupling and the driven side coupling are disengaged from each other, and therefore the link of driving of the housing side and the rotary body side is released. With this configuration, the above-described drive transmission device is preferably used in the image forming apparatus.